The research is planned to study the metabolic interrelationships between three toxic environmental pollutants: cadmium, mercury, and lead, along with two essential trace metals, zinc and copper. In the organism all five trace metals can bind to metallothionein, which in turn is synthesized in response to cadmium challenge. The physiological importance of metallothionein will be elucidated; primary emphasis will be given to investigate the probable role of metallothionein in the detoxification of cadmium, mercury, and lead. Exposure to cadmium is suspected as an important factor in the causation of essential hypertension in experimental animals as well as in human population. The validity of this concept will be tested in rats, and efforts will be made to investigate the possible involvement of metallothionein in the etiology of hypertension.